This invention relates to compositions and methods for removing hardened or semi-hardened cementitious substances such as concrete, paster, grout, mortar and similar substances from surfaces.
There is a significant problem, particularly in the construction industry, with concrete being inadvertently poured or splashed across surfaces on which is desired that concrete not be applied. When the concrete is still soft it is relatively easy matter to simply wash away the concrete with water. However, frequently concrete splashes occur in situations where the concrete cannot be immediately removed or is not noticed for some time. In these cases, the concrete hardens and can be very difficult to remove. Also, removing such hardened concrete can cause damage to the surface from which the concrete is removed.
Similar problems can also occur when plastering either internal or external building surfaces or when working with grout, mortar and similar substances.
Known removal compositions and methods include the use of strong inorganic adds which attack concrete when applied directly on to the concrete and allow the concrete to be removed, for example by being washed away with water flowing from a hose.
Such known compositions have significant disadvantages. The major disadvantage is that the use of strong inorganic acids is unfriendly to the environment. Although these substances can be very effective in removing concrete, they produce residual substances which are biologically toxic and which are therefore undesirable.
The other significant disadvantage with the known compositions is that the inorganic, acids are strong acids and pose a significant risk of damage of the surface upon which the concrete is disposed. For example, surfaces from which concrete is designed to be removed are usually surfaces of buildings including exterior cladding and paint work, windows and window frames. Other surfaces include the exterior surfaces of private vehicles such as automobiles which are parked in the vicinity of a construction site and which get sprayed with concrete inadvertently during a construction operation. These surfaces are obviously sensitive and are easily damaged by strong acids.
It is an object of the present invention to provide compositions or methods for removing cementitious substances which will at least go some way toward overcoming the foregoing disadvantages, or which will at least provide the public with a useful choice.
Accordingly, in one aspect the Invention may broadly be said to consist in a composition for removing a cementitious substance from a surface, the composition including
citric acid, and
an organic thickening agent.
In a further aspect the invention may broadly be said to consist in method for removing a cementitious substance from a surface, the method comprising the steps of applying a composition of citric acid and an organic thickening agent to the concrete, allowing the composition to remain in contact with the concrete until such time as the concrete has been substantially transformed to a state whereby it may be removed from the surface, and
removing the transformed concrete from the surface or allowing the transformed concrete to fall away from the surface.